Car dumper dust collection method and apparatus

ABSTRACT

An apparatus for rotary dumping of rail cars, including a material receiving pit. A rotary rail car dumper includes a rotational frame supporting at least one baffle. The rotational frame is configured to dump a load from a rail car during rotational motion of the rotational frame between an upright position wherein the entire load is in the rail car and a dumping position wherein the load can exit the rail car. A backside airflow diverter is located beneath the rotational frame and includes a curved upper surface. A lower margin of the at least one baffle contacts the curved upper surface during at least part of the rotational motion of the rotational frame. A backside hood is located beneath the backside airflow diverter on the back side of the pit.

RELATED APPLICATIONS

This application is a continuation of application Ser. No. 12/822,845filed Jun. 24, 2010 now U.S. Pat. No. 7,988,401, which is a continuationof application Ser. No. 11/981,618 filed Oct. 31, 2007 now U.S. Pat. No.7,811,041, which is a continuation of application Ser. No. 11/235,655filed Sep. 26, 2005 now U.S. Pat. No. 7,322,785, which is acontinuation-in-part of application Ser. No. 10/159,808, filed May 31,2002 now U.S. Pat. No. 6,960,054, which claims the benefit of U.S.Provisional Application No. 60/294,809 filed May 31, 2001 all of whichare incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to rotary-dumping of material from railcars, and more particularly, to a method and apparatus for controllingenvironmental contamination produced by rotary-dumping material fromrail cars.

BACKGROUND OF THE INVENTION

Rail cars have been used for many years to efficiently haul largequantities of bulk materials over land. Items commonly shipped includegrain, iron ore and coal. Shipping such items via rail car is veryefficient due to the ability to transport extremely large loads of thesematerials in one shipment. For example, one single rail car may hold upto 110 tons of coal and an entire train made up of such cars may be over130 cars in length, extending 6000 feet in total length.

Once at the destination, it is necessary to unload the cargo. For bulkmaterial such as grain, ore, or coal, bottom-dumping and rotary-dumpingare commonly used. Bottom-dumping involves staging a particular car overa receiving pit and opening hatches located in the bottom of the car.The cargo exits the car though the bottom hatches or doors and proceedsinto the pit below. U.S. Pat. No. 5,302,071, assigned to SvedalaIndustries, Inc., discloses one example of a bottom-dumping rail car.

Bottom-dumping requires the use of rail cars that are specificallydesigned for bottom-dumping. This is due to the need to direct the carcontents to a centrally located chute on the bottom of the car. Thesides of the car must be at least partially sloped to urge the contentstowards the chute, or else there would be a partial retention of thematerial being carried. This configuration decreases the ratio of thecar's size vs. cargo capacity. Additionally, the bottom-dump configuredrail cars are not easily interchangeable with standard cars at adumpsite because the dump apparatus for standard cars must be uniquelyconfigured to accommodate bottom-dump cars. The bottom-dump rail carsare also environmentally disadvantageous, as will be described morefully below.

Rotary-dumping is the other commonly used method of unloading a railcar. In rotary-dumping, a standard rectangular rail car is staged orindexed in a rotary-dump apparatus. The apparatus then rotatesapproximately one-half turn, thereby dumping the contents of the carinto a receiving pit. Typically, the cars of the train remain connectedduring the dumping process through the use of rotary couplings betweeneach car. Such couplings permit the cars to be rotated while stillconnected though an axis center at the coupling. U.S. Pat. Nos.4,479,749 and 4,609,321, both assigned to Dravo Corporation, discloseconventional rotary-dump apparatuses. In some applications, such as thedumping of coal at major power plants, cars may be rotated and emptiedat the rate of one car every four minutes.

Environmental pollution is an important concern to the design of amaterial dumping facility. When the car's load is dumped, a largequantity of material exits the car in a very short time. The turbulencegenerated by the quick unloading causes fine dust particles to billow upfrom the receiving pit and pollute the air surrounding the dumpfacility. The resulting dust, such as from grain or coal, is veryexplosive when in sufficient density. It is also an environmentalpollutant. Therefore, there is a need to provide an apparatus and methodfor minimizing the polluting effect of dust.

Bottom-dump apparatuses have two critical drawbacks. First, they requirespecial cars equipped with the bottom chutes as discussed previously.Second, the dust cloud produced by bottom-dumping is recognized by thoseskilled in the art to be larger, more aggressive and less controllablethan the cloud produced by the rotary-dump method.

Rotary-dump systems control the dust cloud by using fans with largemotors to exhaust the dust-filled air surrounding the car thoughconduits and into filtering devices. This process requires a very highflow of air and correspondingly very large motors to drive such highcapacity system. These motors are commonly several hundred horsepower.Multiple motors of this size may be required at any given installation.

The cloud is typically large enough and aggressive enough to overpowerany given removal system. Therefore, the airflow around the car and inthe pit is controllably designed to keep the dust cloud suppressed longenough to allow the dust collection system to suck the dust from thesurrounding area. The better the airflow is managed, the less horsepoweris needed to drive the system. This results in greatly improvedefficiency.

The Dravo patents listed above disclose a method of enclosing a rail carwithin a fixed enclosure. This design has several drawbacks. First, itrestricts the operator's ability to observe the load as it is beingdumped to ensure that the system does not malfunction and that noimpurities or foreign objects are introduced into the pit. Next, thefixed enclosure requires multiple large motors to drive the plurality ofair handling units. The filtering portions of the air handling units arewithin the dumping facility, which makes cleaning and maintenance moredifficult. The presence of the air filtering units in the dumpingfacility exposes the facility to the risk of damage due to the force ofexplosions that sometimes occur in the filtering assemblies. Finally theefficiency of the system is low due to the large motors required toproduce sufficient air removal capacity because the control of theairflow around the car does not have good dust cloud retention time.

There are two different types of rotary car dumpers in common use. Thoseskilled in the art refer to the two types of dumpers as rings outdumpers and rings in dumpers. The rings referred to are the structuralends of a car dumper which support the entire car dumper barrel and therailcar itself. Depending upon the design of a rotary car dumper it mayhave the rings located at the far ends of the dumper barrel, a rings outdesign, or it may have the rings located approximately one quarter ofthe length of the barrel in from the ends, the rings in design.

When a railroad car is dumped more air is displaced by the rush ofproduct exiting the railcar than can be evacuated by a blower system ina period of time during the dump. Thus, there is a tendency for themoving dust laden air to escape from the car dumper pit by any exit paththat may be available.

In the case of a rings out car dumper the dust laden air tends to escapebeneath the end ring and travel upward between the end ring and thedumper pit wall. Thus, the dump creates an upward escaping cloud of dustladen air above track level. For reasons of air quality andenvironmental protection it is desirable to maintain the dust laden airbeneath the track level within the dump pit area. Dust laden air that isabove track level is harder to control and direct to a blower system fortransport to a dust filter house.

In the case of a rings in car dumper, the dumper pit is often designwith a portion of the dumper pit wall extending under the center line ofthe track. This wall extension is in place to support the trunions that,in turn support the supporting rings and thus the dumper barrel anddumper platen. This wall extension beneath the dumper barrel preventsdumper mounted baffles from extending to the extreme ends of the dumperpit because the dumper mounted baffles would interfere with theprotruding wall while rotating. This arrangement creates a gap betweenthe dumper pit wall and the baffles that is equal to the thickness ofthe wall extension that supports the dumper barrel.

Therefore, there is a continuing need to provide a rotary-dumper dustcollection apparatus and system that overcomes the drawbacks of theprior art.

SUMMARY OF THE INVENTION

The present invention addresses the disadvantages in the prior art andthe need to provide an environmentally friendly and efficient way tounload rail cars by providing a method and apparatus for controllingdust generated by the rotary dumping of rail cars. One or more flexiblebaffles are provided to the back-side of a rotary dump frame to seal aportion of the material receiving pit during a portion of the rotarymotion. The dust cloud generated by this dumping is retained in the pitfor an increased time due to tumbling of the cloud induced by thebaffles and other features of the facility. A plurality of intake ductsremoves the dust cloud from the pit for transfer to a remote filteringfacility.

In a rings out dumper to prevent air from escaping beneath the end ringand traveling upward between the end ring and the dumper pit wall, thepresent invention includes an end ring baffle that protrudes from thegrizzly to above the perimeter of the dumper end ring. The end ringbaffle seals to the ski jump of the backside hood and extends toward theopposite side of the dump pit, sufficiently to prevent any airflow fromescaping beneath the end ring. Thus, the end ring baffle extends fromthe backside hood toward the dump side of the pit. The precise length ofthe end ring baffle is determined by the dumper and pit design. The endring baffle is fit to the grizzly which forms the reticulated top of thedumper pit hopper so that any air from the hopper is channeled upwardpast the perimeter of the end ring so that is unable to escape beneaththe end ring.

In the case of the rings in dumper, the present invention includes anend of hood close off panel. The end of hood close off panel extendsfrom the barrel support wall to the ski jump of the backside hood. Thus,the end of hood close off panel creates a barrier to prevent dust ladenair from escaping the dust containment area. As moveable bafflessuspended from the dumper drum rotate around they first make contactwith the platen support wall and then engage the end of hood close offpanel as they leave the wall. This creates a continuous seal for theremainder of the rotation of the dumper which prevents dust laden airfrom escaping around the end of the baffle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side detail view of a rotary-dump facility according to anembodiment of the present invention;

FIG. 2 is a top view of a rotary-dump facility according to anembodiment of the present invention;

FIG. 3 is a sectional view of a rotary-dump apparatus with airflowcontrol features according to an embodiment of the present invention;

FIG. 4 is a sectional view of the rotary-dump apparatus of FIG. 3 inpartial rotation;

FIG. 5 is a sectional view of the rotary-dump apparatus of FIG. 3 inpartial rotation;

FIG. 6 is a sectional view of the rotary-dump apparatus of FIG. 3 inpartial rotation;

FIG. 7 is a sectional view of the rotary-dump apparatus of FIG. 3 inpartial rotation;

FIG. 8 is a sectional view of the rotary-dump apparatus of FIG. 3 atfull rotational travel;

FIG. 9 is a sectional view of a rotary-dump apparatus with airflowcontrol features according to an embodiment of the present invention atpartial rotation;

FIG. 10 is a sectional view of the rotary-dump apparatus of FIG. 9 inpartial rotation;

FIG. 11 is a sectional view of the rotary-dump apparatus of FIG. 9 atfull rotational travel;

FIG. 12 is a partial detail end view of a rotary-dump apparatusaccording to an embodiment of the present invention;

FIG. 13 is a detail end view of a rotary-dump frame with baffleaccording to an embodiment of the present invention;

FIG. 14 is a detail view of a baffle according to an embodiment of thepresent invention;

FIG. 15 is a detail end view of a rotary-dump frame with baffleaccording to an embodiment of the present invention;

FIG. 16 is a detail view of a baffle according to an embodiment of thepresent invention;

FIG. 17 is a detail view of a baffle according to an embodiment of thepresent invention;

FIG. 18 a is a side elevational view of a baffle for a rotary-dumpapparatus according to an embodiment of the present invention;

FIG. 18 b is a side elevational view of a baffle for a rotary-dumpapparatus according to an embodiment of the present invention;

FIG. 19 is a sectional side view of a rotary-dump apparatus according toan embodiment of the present invention taken along line 2-2 of FIG. 2;

FIG. 20 is a sectional side view of a rotary-dump apparatus according toan embodiment of the present invention taken along line 3-3 of FIG. 2;

FIG. 21 is a partial top detail view of a rotary-dump apparatusaccording to an embodiment of the present invention;

FIG. 22 is a partial top detail view of a rotary-dump apparatusaccording to an embodiment of the present invention;

FIG. 23 is a sectional view of a rings out rotary-dump apparatus inaccordance with the present invention;

FIG. 24 is a sectional view taken along elevational line 24-24 of FIG.23;

FIG. 25 is a sectional view taken along section line 25-25 of FIG. 23;

FIG. 26 is a sectional view taken along section line 26-26 of FIG. 23;

FIG. 27 is a detailed sectional view taken from FIG. 26;

FIG. 28 is a sectional view of a rings in rotary dumper in accordancewith the present invention;

FIG. 29 a is a front elevational view of an end of hood close off panelin accordance with the present invention;

FIG. 29 b is an end elevational view of end of hood close off panel;

FIG. 29 c is a plan view of end of hood close off panel;

FIG. 30 is a schematic plan view of a rings out rotary dumper facility;and

FIG. 31 is a schematic plan view of a rings in rotary dumper facility.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, a material dumpsite 50 is shown. Throughoutthis description, reference will be made to the configuration of thepresent invention for use at a coal dumping facility. However, theinvention is well suited to the dumping of a wide range of dustproducing materials, such as ore and grain.

The coal dumpsite 50 generally comprises a dumping facility 52 and afilter facility 54. The material to be dumped enters the dump facility52, which is a rotary-type dump facility. The dumping of this materialproduces a dust cloud, which is sucked through ductwork and transferredto the filter facility 54 through air transfer ducts or conduits 56.

The filter facility 54, also known as a bag house, functions to separatethe coal dust particles from the air to prevent environmentalcontamination and the possibility of explosion.

Bag houses 54 generally comprise an upper portion 55 and a lower portion57 separated by a filter membrane assembly (not shown). The contaminatedair is drawn through the filter assembly, and the filter assembly trapsthe contaminants in the lower portion 57 of the filter facility.Filtered air proceeds to the upper portion 55 of the filter facility 54and exits through filtered air exit 58. The filtered air arrives at fanhousing 62 and finally exits through a clean air exhaust duct 60. Adrive motor 64 powers a fan (not shown) within fan housing 62. The drivemotor 64 rotates the fan, which causes air to rapidly move through theentire system as described hereinabove. The negative pressure createdwithin the system, located prior to the fan housing, drives the systemby drawing the contaminated air into the system of the rotary-dumpfacility 52.

A contaminant particle collector 68 is disposed within filter facility54 and in communication with the facility lower portion 57 to collectthe contaminant particles that accumulate on the filtering assembly.From time to time, the filtering assembly may be vibrated or flushedwith a reverse flow of air in order to remove accumulated contaminants.The filter assemblies and filter facility 54, as described herein, aremore fully described in co-pending U.S. patent Ser. No. 10/037,319,which is hereby incorporated by reference.

The filter facility 54 may comprise more than one fan housing 62 anddrive motor 64, as shown in FIG. 2. The ultimate number of drive motorsdepends on the capacity of the system in the particular installation andsize of the individual motors utilized. A plurality of explosion vents66 is provided to each of the upper and lower portions of the bag house54.

In the event that a fire or explosion might occur in the bag house 54,the explosion vents 66 minimize potential damage. The powder from coalor grain dust is highly explosive, as discussed previously. Theexplosion vents 66, in conjunction with a remote filter facility 54avoid damage to the dumping facility 52, which is in contrast to adumping facility that encloses the filtering facility within the samehousing as the dump facility.

Referring to FIG. 3, the coal dump facility 52 is shown with a coal car69 in the upright configuration. The contaminated air enters thetransfer duct 56 through a plurality of air inlet conduits 70, 72. Thedump-side intake 70 is located on the side closest to the direction ofthe dumping and the back side intake 72 is located approximatelyopposite the dump-side intake 70. Each intake 70, 72 terminate in arespective dump-side hood 74 and backside hood 76. The intakes 70, 72exhaust the contaminated air that emanates from the pit 78, which islocated directly below the rotational dumping frame 80. Each of theintakes 70, 72 spans the length of the pit 78, as will be describedbelow.

The pit 78 presents a plurality of features to cooperate in controllingthe movement of the dust cloud produced by a dumping activity. Adump-side diverter 82 is positioned on the dumping side of the pit 78.The dump-side diverter 82 functions to both direct the flow of materialbeing dumped, and to direct the airflow inside the pit 78. A backsideairflow diverter 84 is positioned in the pit 78 approximately oppositeof the dump side diverter 82. The backside diverter 84 is also referredto as the ski jump, due to the resemblance of its general shape.

The ski jump 84 comprises a curved upper surface 86 and lower surface88. The backside hood 76 exhausts the dusty air from the pit 78 frombeneath the lower surface 88 of the ski jump 84. The sloped uppersurface 86 cooperates with features on the rotational frame 80 to sealthe backside of the frame 80 and control the airflow during a dumpingoperation.

A dump-side hood baffle 90 protrudes from a portion of the side of thedump side hood 74. This baffle 90 is a flexible rubber member that spansthe width of the pit 78. The baffle 90 is preferably a 3/16 inch thickbelt comprised of 2-ply Dulon and 150# polyester. Baffle 90 ispreferably of sufficient length to droop into the pit area 78. Thedump-side baffle 90 functions to control the airflow in the pit andinduce a tumbling effect to the dust cloud caused by a dumpingoperation. The amount of time a dust cloud is retained in the pit isincreased by making the cloud tumble, rather than naturally billowingstraight up. Thus, the air intakes 70, 72 have more time to exhaust thedust cloud than if no dust cloud tumbling were provided.

A grizzly 92 defines the bottom of the dumping pit 78. A hopper 94, asshown in FIG. 1, is disposed below the grizzly 92. The grizzly 92comprises a grid that screens impurities from the coal in car 69 thatare larger than the aperture size in the grid. These impurities mayinclude rocks and timber. The hopper 94 funnels the coal into areceiving pit, transport container or conveyor for transportation,storage or later use.

The rotational frame 80 comprises a section of track 94 that isapproximately the same length as a rail car 69. The track 94 is sealedbelow, on the dump side and on the back side by plates 96 to prevent theescape of dust during a dumping operation. Each of the front 81 and backends 83 of the rotational frame 80 are fastened to end plates 98 (shownin FIG. 2). The end plates 98 are configured to permit the rotation ofthe frame 80 about an axis centered at the coupling of the rail car 69,thereby permitting the cars 69 to remain coupled during a dumpingoperation. The rotational frame 80 receives a plurality ofcounterweights 100 to balance the car 69 and frame 80 during rotationalmotion.

A plurality of frame baffles 102 are provided to the dump side 81 ofrotational frame 80. Referring to FIGS. 3, 12, 13 and 15, the baffles102 are placed at multiple positions on the dump side of the rotationalframe 80. FIG. 3 depicts three baffles 102 mounted to the frame 80 viahinged 103 fasteners. Such arrangement is shown with more detail in FIG.17. The hinges 103 allow the baffles 102 to hang vertically regardlessof the orientation of the rotational frame 80, as shown in FIGS. 3though 8.

FIGS. 14 and 16 depict an alternative mounting configuration for thebaffles 102. An extension member 104 extends from the plate 96 to afixed distance. The extension member is rigid. The baffle 102 is thenfastened to the end of the extension member 104 via a hinged fastener103, as in FIG. 17, or by way of a fixed bracket 106, as shown in FIG.14. A further alternative involves fastening the fixed bracket 106directly to the side of the frame 80 or plate 96 without an extensionmember 104, as shown in FIG. 16.

FIGS. 18 a and 18 b depict a baffle 102 according to a preferredembodiment. The baffle 102 comprises a top edge 108, bottom edge 110,first side edge 112, second side edge 114, two longitudinal sidesurfaces 116, 118 and leading edge 119. The baffles 102 preferablyextend the approximate length of the pit 78, which is slightly longerthan the length of a rail car 69. Alternatively, a baffle 102 maycomprise a series of baffle segments that, when operated as an assembly,are equivalent to a single baffle 102 spanning the approximate width ofthe pit 78.

Each baffle 102 is preferably fastened to a mounting bracket 106 by wayof a plurality of threaded fasteners 107 extending through a respectiveplurality of apertures 120 in baffle. The apertures 120 communicatebetween the longitudinal surfaces 116, 118 of the baffle 102 and areequally spaced about a line adjacent the top 108 of the baffle 102. Athreaded bolt 132 is provided with a washer 134 (to minimize tearingthrough the aperture) to sandwich a portion of the baffle between thewasher and a surface of the mounting bracket. The opposite surface ofthe bracket receives a locking washer (not shown) and threaded nut 136.Those having skill in the art will recognize that other means forfastening the baffles 102 to the mounting brackets 106, such as clampsand adhesives, may be used without departing from the spirit and scopeof the present invention. The baffles 102 are preferable made from thesame material as the dump-side hood baffle 90. However, any flexible andrugged material may be used within the scope of the present invention.

Referring to FIGS. 3 through 8, three baffles 102 are shown onrotational frame 80 throughout various points of a dumping cycle.Embodiments using fewer or greater numbers of baffles 102 arecontemplated by the present invention. In FIG. 3, the frame 80 is in afull upright position. FIG. 4 shows the frame 80 rotated throughapproximately 60 degrees of motion. The first 122 of three baffles, 122,124, and 126, is arched due to contact with the ski jump 84. The lengthof each baffle 122, 124, 126 is preferably such that it will bowslightly, as shown in the figures, when contacting the upper surface 88of the ski jump 84.

FIG. 5 shows the frame 80 at 90 degrees of rotation. Now, each of thefirst 122 and second 124 baffles are atop the ski jump 84, therebycausing the baffles 122, 124 to bow. The contact between the uppersurface 86 of the ski jump 84 and the leading edge 119 of the baffles122, 124, 126 effectively bars the dust cloud from escaping out thebackside of the dumping frame 80. The cloud is sealed in the pit 78until removed by the ducts 70, 72.

FIG. 6 shows the frame 80 at approximately 110 degrees of rotation. Now,only the second 124 of the baffles 122, 124, 126 is in contact with theski jump 84. This illustrates the point that, starting at approximately60 degrees of rotation, one or more of the number of baffles 122, 124,126 is in contact with the ski jump 84 to provide a seal on the backsideof the frame 80.

FIG. 7 shows the frame 80 at approximately 130 degrees of rotation. Now,the third baffle 126 is in contact with the ski jump 84 and the firstbaffle 122 is completely past the jump 84. The frame 80 continues itsrotation until coming to 160 degrees of rotation as shown in FIG. 8. Onehundred sixty degrees (160°) is a complete dumping motion for thedepicted embodiment. Typically, the rail car 69 need not be rotated morethan hundred sixty degrees (160°) to achieve full dumping.

The baffles 102 also provide the additional benefit of scraping the topsurface 86 of the ski jump 84 with the leading edge 119 when the car 69is rotated in the opposite direction. The scraping action shovels anyaccumulated dust off of surface 86. This configuration results in aself-cleaning mechanism, which minimizes the need to periodically cleansurfaces in the dump facility.

FIGS. 9, 10 and 11 depict an alternative embodiment of the presentinvention wherein the rotary-dump facility 52 is configured to allow fora 180 degree dumping motion, while continuing to manage the airflow aspreviously discussed. These figures also illustrate that acounterclockwise direction dumping motion may be employed withoutdeparting from the spirit and scope of the present invention. Threebaffles 122, 124, 126 are again shown as being hingedly fastened to thedump frame 80. The second 124 and third 126 baffles are now disposed onprotruding extension members 104. A rigid airflow diverter member 127 isshown mounted in place of the hood baffle 90 to create the tumblingeffect on the dust cloud within the pit 78.

The configuration of the ski jump 84 is modified with respect to thatshown in FIGS. 3-8 to accommodate the additional 20 degrees of rotationwithout structural interference between the ski jump 84 and the frame80. The sloped surface 86 of the ski jump 84 does not extend past theend of the backside hood 76 to provide the required clearance. FIG. 9shows that the upper surface 86 of the jump 84 no longer extendsvertically above the backside hood 76, as it did in FIG. 3. FIGS. 9-11show the frame 80 at 20°, 110° and 160°, respectively. The frame 80 maycontinue to rotate until reaching 180° without interference from thevarious dumping structures.

Referring to FIGS. 19 through 22, various views of the rotary-dumpfacility 52 are shown to illustrate the hood 74, 76 and duct placements70, 72 according to the preferred embodiment. FIG. 19 shows a sidesectional view of the dump side of the dump facility 52. A plurality ofdump side air intake ducts 70 branch off of the transfer duct 56. Eachbranch 70 terminates in a hood 74. The hoods 74 are approximatelyaligned with the top of the pit 78. The hoods 74 span almost the entiredistance between the end plates 98.

The operator station 128 is also shown in FIG. 19. The operator station128 is generally placed above the dump side of the rotational frame 80to provide the operator with a clear view of the pit area 78 and thegrizzly 92. This way, the operator may observe the dumping procedure toensure safety and efficiency. Prior art systems that completely enclosethe rail car 69 do not permit the operator to easily observe a dumpingprocedure.

FIG. 20 shows a side sectional view of the backside of the dump facility52. A plurality of backside air intake ducts 72 branch off of thetransfer duct 56. Each branch terminates in a hood 76. The hoods 76 arepositioned near the bottom of the pit 78. The relative positions of thedump-side 74 and backside 76 hoods may also be seen in FIG. 3. The hoods76 span almost the entire distance between the end plates 98.

FIG. 21 shows a top partial sectional view of the dump side intakes 70and respective hoods 74. There are only relatively small gaps 138between adjacent hoods 74, 76. The minimal gaps 138 create a generallyconstant wall of suction to remove the dust cloud quickly. FIG. 22 showsa top sectional view of the backside hoods 76. The upper surface 86 ofthe ski jump 84 is outlined as a location reference.

A major design goal for a dump-site 50 is to balance the systemeffectiveness with its efficiency. It is theoretically possible toremove a volume of air sufficient to dismiss the dust cloud withoutusing any sealing systems. However, such systems would require enormousdrive motors and would be undesirably inefficient. Therefore, it is aconstant design goal to reduce the airflow to around 140,000 cubic feetper minute. The present invention provides a system and method thatallows those design goals to be achieved in the preferred embodiments.To help achieve this goal, approximately 60 percent of the air volume ispreferably removed from the backside duct system 72. The remaining 40percent is removed from the front or dump side 70. The air duct hoods74, 76 are spaced so as to achieve an even air distribution along theentire length of the dump frame 80.

Increasing the time the dust cloud is retained in the pit 78 allows alower volume system to work effectively. Configuring the system asdescribed herein and shown in the figures increases the retention timeby tumbling the air below the dump frame 80 in the pit 78. The tendencyof the tumbling air is to remain in the sealed confines of the pit 78,rather than seeking to escape. The baffles 102 and other featuresdescribed herein contribute to this tumbling effect.

Referring to FIGS. 29 a, 29 b and 29 c, end of hood close off panel 222includes arcuate shaped flat portion 228 and angled panel 230. End ofhood close off panel 222 is secured to platen support wall 224 byfasteners 232.

Referring to FIGS. 30 and 31, FIG. 30 depicts a rings out dumperfacility 200. FIG. 31 depicts a rings in dumper facility 202. Referringto FIG. 30, in a rings out dumper facility 200 supporting rings 204 arelocated at the far ends of the car dumper 206. Referring to FIG. 31, ina rings in dumper facility 202 supporting rings 204 are located somedistance inboard of the ends of car dumper 206.

Referring to FIG. 23, rings out dumper facility 200 generally includessupport rings 204, car dumper 206, dumper platen 208, supported rail car210, grizzly 212, dual wheel trunion 214 and end ring baffle 216.Support rings 204 support dumper platen 208 of car dumper 206. Railcar210 is supported by dumper platen 208. Grizzly 212 is at the bottom ofrings out dumper facility 200. Grizzly 212 is a grating with openingsthrough which dumped material may fall. Dual wheel trunion 214 supportssupporting rings 204 thus, supporting car dumper 206 as it turns.

Referring to FIGS. 23-27, end ring baffle 216 is located near to dumperpit wall 218 but inside of supporting ring 204. End ring baffle 216 isattached to the end of and extends upwardly from grizzly 212. End ringbaffle 216 extends upwardly slightly beyond perimeter 220 of supportingring 204. The edge of end ring baffle 216 generally follows theperimeter 220 of supporting ring 204.

End ring baffle 216 is secured to grizzly 212 and caulked along itslength to create a dust and air resistant shield. End ring baffle 216 isalso secured to backside hood 76. Referring to FIGS. 24 and 26, belting226 may be utilized along the edge of backside hood 76 to seal backsidehood 76 to supporting ring 204.

Referring particularly to FIG. 27, end ring baffle 216 is secured andsealed to the edge of grizzly 212.

Referring now to FIGS. 28, 29 a, 29 b, and 29 c, rings in dumperfacility 202 generally includes car dumper 206, dumper platen 208,grizzly 212, railcar 210, and end of hood close off panel 222. End ofhood close off panel 222 extends from platen support wall 224 tobackside diverter 84 (also known as the ski jump). End of hood close offpanel 222 thus creates a barrier to prevent dust laden air from escapingthe containment area.

As baffles 102 rotate they first make contact with platen support wall224 and then engages end of hood close off panel 222. This arrangementcreates a continuous seal for the remainder of rotation of the cardumper 206, eliminating an escape path for dust laden air around the endof baffle 102.

In operation, a coal car 69 enters the rotary-dump facility 52 throughentrance 130. The car 69 may be coupled to adjacent cars with a rotarycoupling. The car to be dumped 69 is indexed on to track 76. Therotational frame 80 begins rotating the car 69 through a full dumpingrotational motion of between 160 and 180 degrees, depending on facilitydesign. As the car 69 is rotated, the material, such as coal, within thecar 69 spills over the dump side of the car 69. The car 69 exits thefacility 52 through an exit 131 after dumping is completed and the car69 is returned to its upright position.

The dumping of the material generates a dust cloud. The cloud isretained in the pit 78 by sealing plates 96, 98 on the dump frame 80 andby the use of a plurality of baffles 102. The baffles 102 and facility52 design features, such as diverters 82, 84 hood baffle 90 and intakehoods 74, 76 cause the dust cloud to tumble within the pit 78, therebyincreasing the retention time of the dust cloud within the pit 78.

A plurality of intake hoods 74, 76 on both the dump side and back sideof the frame 80 inhale the dust cloud and transmit the contaminated airthrough a transfer duct 56 to a remote filter facility 54. The dirty airenters a lower portion 57 of the facility 54 and is passed through afilter assembly before arriving at an upper portion 55 of the facility54. The filter assembly traps the airborne contaminants in the lowerportion 57 of the facility. The clean air continues through a filteredair exit duct 58, through a fan housing 62 and exits to the atmospherethough a clean air exhaust duct 60.

In operation, end ring baffle 216 extends above grizzly 212 and beyondperimeter of supporting ring 204. Thus, end ring baffle 216 seals offthe space beneath supporting ring 204, thus, preventing dust laden airfrom exiting dumping facility 252. Thus dust laden air is retained inpit 78 until it can be removed by air flow.

End of hood close off panel 222 creates a barrier between platen supportwall 224 and backside diverter 84 thus blocking off a path of escape fordust laden air. End of hood close off panel 222 seals dust laden air inpit 78 until it can be removed by air flow.

Although the present invention has been described with reference to thepreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A method of modifying an apparatus for rotarydumping of rail cars to reduce dust pollution, wherein the apparatus mayoptionally already include a backside hood, the method comprising:adding at least one baffle to a rotational frame disposed at leastpartially in a pit, the rotational frame configured to dump a load froma rail car during rotational motion of the rotational frame between anupright position wherein the entire load is in the rail car and adumping position wherein the load can exit the rail car; adding abackside airflow diverter within the pit adjacent a back side of thepit, wherein the backside airflow diverter includes a curved uppersurface and a lower margin of the at least one baffle contacts thecurved upper surface during at least part of the rotational motion ofthe rotational frame; assessing the apparatus to determine whether thebackside hood is already present; adding the backside hood at a locationbeneath the backside airflow diverter on the back side of the pit if thebackside hood is not already present.
 2. The method of claim 1, furthercomprising positioning and sizing the at least one baffle on therotational frame such that the at least one baffle is in contact withthe curved upper surface of the backside airflow diverter when therotational frame is rotated more than sixty degrees from a horizontalplane.
 3. The method of claim 1, further comprising adding a dump sideairflow diverter and locating the dump side airflow diverter at leastpartially disposed in the material receiving pit.
 4. The method of claim1, further comprising hingedly fastening the at least one baffle to therotational frame.
 5. The method of claim 4, further comprisingpositioning the curved upper surface of the backside airflow diverter tocause the at least one baffle to hingedly rotate in relation to thebackside airflow diverter.
 6. The method of claim 1, further comprisingpositioning a leading edge of the at least one baffle to scrape thecurved upper surface during a return portion of the rotational motion.7. The method of claim 1, further comprising coupling the backside hoodin fluid communication with a filter facility.
 8. A rotary rail cardumper, comprising: a rotational frame supporting at least one baffle,the rotational frame configured to dump a load from a rail car duringrotational motion of the rotational frame between an upright positionwherein the entire load is in the rail car and a dumping positionwherein the load can exit the rail car; a backside airflow diverterbeneath the rotational frame, wherein the backside airflow diverterincludes a curved upper surface and a lower margin of the at least onebaffle contacts the curved upper surface during at least part of therotational motion of the rotational frame; a backside hood locatedbeneath the backside airflow diverter on the back side of the pit. 9.The rotary rail car dumper as claimed in claim 8, wherein the at leastone baffle on the rotational frame is sized and positioned such that theat least one baffle is in contact with the curved upper surface of thebackside airflow diverter when the rotational frame is rotated more thansixty degrees from a horizontal plane.
 10. The rotary rail car dumper asclaimed in claim 8, further comprising a dump side airflow diverter andlocated at least partially disposed in the material receiving pit. 11.The rotary rail car dumper as claimed in claim 8, further comprising ahinge fastening the at least one baffle to the rotational frame.
 12. Therotary rail car dumper as claimed in claim 11, wherein the curved uppersurface of the backside airflow diverter is positioned to cause the atleast one baffle to hingedly rotate in relation to the backside airflowdiverter.
 13. The rotary rail car dumper as claimed in claim 8, furthercomprising a leading edge of the at least one baffle that is positionedto scrape the curved upper surface during a return portion of therotational motion.
 14. The rotary rail car dumper as claimed in claim 8,wherein the backside hood is coupled in fluid communication with afilter facility.